Method and mechanism for processing elongated metal articles



y 1960 .1. c. BONGIOVANNI 2,937,431

METHOD AND MECHANISM FOR PROCESSING ELONGATED METAL ARTICLES Filed June7, 1955 4 Sheets-Sheet 1 1 INVENTOR. JOHN C. BflNG/OVANNI BY *3 MTLMJL ATTOE VfXi.

Filed June 7, 1955 J. c. BONGI'OVANNI 2,937,431 METHOD AND MECHANISM FORPROCESSING ELONGATED METAL ARTICLES 4 Sheets-Sheet 2 .ifig. 5

IN VEN TOR.

JOHN qzoA/clol Alvw/ ATTOR/VlYS- May 24, i960 Filed June 7, 1955 METHODAND MECHANISM FOR PROCESSING J c. BONGIOVANNI 2,937,431

ELONGATED METAL ARTICLES 4 Sheets-Sheet 3 INVENTOR.

JOHN C. BON/Ol/A/VN/ ATTORNEY-5,

May 24, 1960 J. c. BONGIOVANN1 2,937,431

METHOD AND MECHANISM FOR PROCESSING I ELONGATED METAL ARTICLES FiledJune 7, 1955 4 Sheets-Sheet 4 INVENTOR. Mil/V CBflN/OVA/V/V/ A T TORNEY5.

METHOD AND MECHANISM FOR PROCESSING ELONGATED METAL ARTICLES John C.Bongiovanui, University Heights, Cthio, assignor to The OsbornManufacturing Company, Cleveland, Ohio, a corporation of Ohio Filed June7, 1955, SenNo. 513,641

14 Claims. (Cl. 29-81) This invention relates as indicated to a novelmethod and mechanism for processing elongated metal articles, and moreparticularly to a method of regularizing and surface beneficiating steelstrip, sheet and the like.

The steel industry with its present hot rolling practice is confrontedwith a difficult problem of scale removal from the hot rolled steelbefore the latter can be further cold rolled or processed. Such scale oroxide on the usual low carbon hot rolled steel comprises three principallayers. The layer next to the steel is chiefly FeO or mixture of Fe andFe O the outer layer is composed chiefly of Fe O and the intermediatelayer which is relatively thick and not usually substanitally attackedby sulphuric acid during pickling is composed chiefly of Fe O The scaleas a whole, however, after fracturing is not impervious to acid, and thepresent conventional practice for removing scale from hot rolled steelstrip, rod and the like is pickling in sulphuric acid which is efiectiveto penetrate to the parent metal underlying the oxide layers. It haslong been recognized that such pickling operations are expensive,timeand space-consuming, and wasteful of materials. With the increasingstrictness of anti-pollution laws, there is also increasing difiicultyin disposing of the spent liquor.

Numerous efforts have been made in the past to remove scale by othermethods including shot blasting and by power brushing. In Pecsok Patent2,335,196 there is disclosed a method of scale removal wherein the steelstrip is first passed between breaker rolls and subjected to a strongwater spray before passing in engagement with power driven rotarybrushes adapted to engage each side of the strip. This and certain othermethods have been found effective to a degree in the removal of oxidescale from steel but the practical difficulty has resided in the factthat any method of scale removal to be adopted as regular steel millpractice, eliminating employment of pickling tanks entirely, must besubstantially 100% reliable. In other words, it is not sufficient that asubstitute method will remove a very large proportion of the scale oreven all of the scale in certain special cases. Before the enormousadvantages to be derived from elimination of the pickling process are tobe realized, it is essential that the new mode of treatment be at leastequally reliable in the removal of the scale. Power brushing representsan extremely attractive mechanical operation for employment in a scaleremoval line inasmuch as such brushing operation, when properlycontrolled and regulated, may also be utilized to beneficiate the metalsurface in other respects and thereby afford a superior product. Inorder for such brushes to be fully effective in scale removal, however,it is necessary that means he provided effective preliminarily tofracture, loosen and otherwise prepare the scale for complete removal bythe brush or brushes. The employment of scale breakers as suggested inthe aforesaid Pecsok Patent 2,335,196 is obvious for such .purpose, butunfortunately those previously known and used in steel mills have notproven fully adequate for the purpose. It is accordingly a principalobject of my inatent V vention to provide novel mechanical means forflexing hot rolled steel strip and the like in a manner eflective toprepare the same for complete removal of oxide scale therefrom by thesubsequent action of properly selected and arranged power driven rotarybrushes.

A further object is to provide a novel roll stand for flexing the workabout a relatively small radius, the rolls being mounted, driven andcontinuously acted-upon in a manner to maintain their uniformlyeffective cooperative action on the strip.

Still another object is to provide such method and mechanism whereby thescale being fractured is subjected both to tension and to compressionstrains.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description and the annexeddrawing setting forth in detail certain illustrative embodiments of theinvention, these being indicative, however, of but a few of the variousways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is an end elevational view of a roll stand incorporatingmechanism embodying my new invention;

Fig. 2 is a longitudinal section through such stand with portions of themechanism further broken away better to illustrate the manner ofassembly;

Fig. 3 is a transverse sectional view through the rolls of such standand illustrating auxiliary brush means acting upon the several rolls toprevent build-up of scale par ticles thereon;

Fig. 4 is a side elevational view of the roll drive mechanism;

Fig. 5 is an end elevational view of the pinion stand of such mechanism;and

Figs. 6 and 7 show in semi-diagrammatic manner the passage of a lengthof strip through a scale removal line utilizing the scale fracturingmeans of the present invention.

Referring now more particularly to said drawing and especially Figs. 1-5thereof, a metal processing mechanism embodying the principles of myinvention is there illustrated comprising two spacedv stands 1 and 2having windows 3 and 4 therein within which are mounted slides 5 and 6respectively journaling a large lower back-up roll 7. Such slides orbearing blocks 5 and 6 are carried .by the pistons 8 and 9 ofdouble-acting hydraulic 'cylinshifted to permit endwise removal of suchbearings and associated rolls when required. 7

Four tie rods 17, 18, 19 and 20 connect the two stands 1 and 2 undertension, such tie rods being enclosed within tubular spacer members suchas 21. A small diameter work roll 22 is mounted to rest upon the uppersurface of lower back-up roll 7, the ends of such work roll beingjournaled in bronze bearings such. as 23 fitting in recesses in theupper surfaces of main slides or bearing mounts 5 and 6 whereby a degreeof vertical movement of such Work roll relative to back-up roll 7 may beobtained. The respective endsof the work roll are engaged by thrustbearings such as 24'terminating in outer housings 25, Screws such as 26threaded in b i k or bndges 27 carried on slides 5 and 6 are adjustableto shift such thrust bearings properly to locate work roll 22. It W111accordingly be apparent that such work roll is precisely positionedaxially but is mounted to float vertically. Roll 22 has no drive of itsown and is rotated only through its engagement with back-up roll 7 andthe travel of the work as later described.

A pair of upper work rolls 28 and 29 are journaled in upper slides orbearing blocks 30 and 31 adapted to be reciprocated vertically withinwindows or slideways 3 and 4 respectively. Such slides or bearing blocksare carried by pistons 32 and 33 respectively, adapted to bereclprocated by double-acting cylinders 34 and 35, synchronism of suchreciprocation being assured by racks 36 and 37 on such pistons adaptedto engage pinions such as 38 on a pinion shaft 39 journaled in therespective stands in the same manner as pinion shaft 12. It isaccordingly ObVlOUS that through reciprocation of bearing slides 30 and31, rolls 28 and 29 may be forced downwardly toward work roll 22, thelatter being supported by large back-up roll 7. Work rolls 28 and 29 aremuch larger than work roll 22 and are asymmetrically disposed relativeto the latter with the axes of rolls 28 and 29 lying in a horizontalplane. As shown in Figs. 1 and 3, the work such as steel strip S isthreaded between lower work roll 22 and upper work rolls 28 and 29, thelatter being operative to enforce conformance of such strip to a portionof the arcuate surface of small roll 22.

Referring now more especially to Figs. 4 and 5 of the drawing, it willbe seen that upper work rolls 2.8 and 29 are driven in unison fromelectric motor 40 whereas lower back-up roll 7 is independently drivenfrom electric motor 41. Motor 40 drives shaft 42 through gear reductionunit 43, and such shaft drives upper pinion 44 in pinion stand 45. Suchpinion in turn engages and drives pinions 46 and 47 which drives shafts48 and 49 coupled to rolls 28 and 29 respectively. Motor 41 drives lowerpinion 50 through gear reduction unit 51, and such pinion in turn drivespinion 52 and shaft 53 coupled to lower back-up roll 7. It isaccordingly possible to vary the rotation of roll 7 relative to that ofrolls 28 and 29.

In order to prevent the build-up of scale particles on the severalrolls, I provide a cylindrical power drivenrotary brush 54 mounted toengage the underside of backup roll 7 and a similar brush 55 mounted toengage the upper surfaces of rolls 28 and 29. A bronze bar 56 isinterposed between the upper portions of rolls 28 and 29 shaped toconform to the arcuate surfaces of the same and also to the outerperipheral surface of brush 55. Such bar is recessed sutficiently topermit brush 55 to engage rolls 28 and 29 but is effective substantiallyto prevent scale particles dislodged by the brush from droppingdownwardly between rolls 28 and 29 onto the upper surface of strip S. Itwill preferably be firmly secured to the end slides to serve anadditional ptupose as explained below.

Suction nozzles 57 and 58 extending the length of work roll 22 areinterposed between roll 28 and roll 7, and between roll 29 and roll 7respectively to remove scale particles from the surface of roll 22.Lengths of brush strip 59 and 60 mounted in such nozzles and engagingroll 22 assist further in cleaning the roll and reducing transfer ofsuch particles from roll 22 to back-up roll 7.

Rotary brush 55 is driven from electric motor 61 through belt 62, pulley63, pulley 64 and belt 65. Brush 54 is similarly driven through anextension of such drive means including belt 66, pulley 67 and belt 68.Brushes 54 and 55 may desirably be carried on swinging arms (not shown)to permit their being conveniently swung out of the way when it isdesired to inspect the rolls, etc.

I very much prefer that two roll stands of the type described above beemployed in sequence to process the traveling strip, the rolls of thesecond stand being inverted relative to the rolls of the first stand sothat the work will be flexed in the opposite direction. A dancing roll69 maybe carried by 'pivotally mounted arms 70 keyed to shaft 71connected to hydromotor 72 whereby a selected rotative force may beapplied to such shaft in a clockwise direction as viewed in Fig. 3 toforce roll 69 downwardly upon the upper surface of the strip S. Suchroll 69 is effective largely to eliminate the upward curling tendency ofthe strip as it leaves the stand and consequently to assist threading ofthe strip through the next stand which, as above indicated, willordinarily preferably include an identical roll assembly which is,however, inverted relative to that of the first stand. When the striphas been threaded through the line, it is ordinarily unnecessarythereafter to maintain downward pressure on the dancing roll 69.

In Figs. 6 and 7 I show a continuous strip processing line incorporatingmy new roll stand and effective both to remove scale from the travelingmetal strip and also to surface beneficiate the same. The metal strip Sis taken from the coil resting on uncoiler 73, and the leading end ofthe strip is first threaded between pinch rolls 74 and feeder rolls 75in stand 76, whence it passes between power driven cylindrical rotarybrushes in duster stand 77 to remove any loose scale, dirt, etc., on theupper and lower surfaces of the strip. The strip is next conductedthrough a stand 78 of the type illustrated in Figs. 1 and 3 anddescribed above, between upper and lower power driven rotary brushes induster stand 79, and then through a second roll stand 80 similar tostand 78 except that the arrangement of the rolls therein is inverted toflex the strip in the opposite direction. After passing through anotherduster stand 81 to remove any loose particles adhering to the surface ofthe strip, the latter passes between pinch rolls 82 and then between therolls of a leveler (which. may, for example, have 11 rolls engaging thework) before passing through another duster stand 85 and slitter 86. Theslit strip may thereafter be conducted through power brushing stands 87,88 and 89 of the type disclosed in co-pending application Serial No.491,992 of Ruben 0. Peterson filed March 3, 1955, entitled,Reciprocating Surface-Finishing Mechanism and Method. The brushes 90,91, 92, 93, 94 and 95 of such latter stands are effective to remove bursfrom the slit strip edges and to surface beneficiate such strip so thatwhen wound on coiler 96 the strip will have been completely de-scaled,cleaned, slit and finished in a single continuous line.

My new strip flexing and working apparatus is of particular utility inpreparing low carbon and alloy steel strip for further treatment by highspeed power driven rotary brushes. The strip will ordinarily be causedto travel at a speed of from 30 to 200 feet per minute and the scaleremoval brushes may be driven at about 8300 surface feet per minute, forexample. Hard crimped steel wire brush bristle material will usually beemployed for this purpose, wire of .0118 inch diameter being suitable.Granular abrasive may be fed to the brushes either externally orinternally as described in Peterson Patent 2,680,938, for example. Theuse of such abrasive, e.g. Aloxite (aluminum oxide), Carborundum, andthe like, is especially advantageous when brushing titanium strip whichtends to adsorb hydrogen, nitrogen and oxygen during its formation toproduce a hard superficial layer desirably removed by my new treatment.Aluminum and high carbon steel strip also .often may be much improved bysuch treatment.

The brush stands 87, 88 and 89 will desirably be mounted on rails forreciprocation transversely of the path of travel of the strip beingtreated, and the brushes utilized will be at least slightly longer thanthe width of the widest strip to be handled by the line. Thereciprocation of the brush supporting carriages will be regulated tocause the ends of each brush closely to approach the corresponding sideedges of the strip being brushed at the inner limits of suchreciprocation. Some or all of such brush stands may desirably bedisposed at angles to the path of travel of the work and also at anglesto each other so that each area ,of the work surface will be powerbrushed in at least three different directions. This arrangementconsiderably enhances the elfectiveness of the brushing operation andaffords a superior finish with pits and other minor surfaceirregularities blended and smoothed. The diagonal placement of the powerdriven rotary brushes is also helpful and effective in removing edgeburs produced by a slitting operation and in blending the sharp surfacejunctures at such edges to form desirably rounded corners.

In some cases, the brushes 90, 91, 92, 93, 94 and 95 may be driven athigh speeds of rotation on the order of about 6,000 or even 9,000surface feet per minute, whereas reciprocation of the brush supportingcarriages transversely of the path of travel of the strip is so slow asto be wholly inconsequential insofar as any modifica' tion of thebrushing action is concerned. Such reciprocation may, for example, be atthe rate of only three complete return reciprocations per minutealthough such reciprocation may also be at a somewhat greater rate ifdesired, without appreciably affecting the action of the brush bristlesupon the work.

Various types of brush drive means may be utilized,

' including fluid motors, and it will be desirable periodically toreverse the direction of rotation of the brushes to maintain thesharpness ofthe bristle ends. The brush bristle material employed willordinarily be relatively hard crimped steel wire which may, for example,have a thin coating of nylon or other plastic thereon, and unlessextremely hard wire is employed the bristle ends tend to become roundedand dulled on the sides first engaging the work, considerably reducingtheir effectiveness. This difliculty may be substantially avoided byperiodically reversing the direction of rotation of the brushes, and forthis reason the drive means may desirably be reversible electric motorsor fluid motors as above indicated. If a sufficient number of brushingstands are utilized, the brushes of one stand at a time may betemporarily retracted out of contact with the work in order that theymay be stopped and their direction of rotation thus reversed. Also, thebrushes of an extra stand which have last been driven in one directionand have since been retracted from contact with the work may now bebrought into operation again in the opposite direction to replacebrushes of another stand due to be retracted and reversed, the newlyretracted brushes becoming extras for similar subsequent employment. Insome cases, however, it is quite satisfactory thus to reverse therotation of the brushes while still in contact with the work or withcontact pressure slightly reduced inasmuch as this can be achieved in avery short period of time. It is also often feasible to time such brushreversal in synchronism with changes in speed of travel of the work andthe passage of strip ends, for example.

The apparatus and method described above .have numerous advantages overconventional pickling methods ordinarily employed in the removal ofscale from strip and the like including the fact that there is little orno loss of virgin metal by brushing as compared with from /2% to as muchas 2% metal less often experienced during pickling. A brushing line ofthe general type illustrated and described will ordinarily occupysomewhat less than one-half the space required by a pickling line. Thepickling acid fumes are highly corrosive in the building and associatedequipment and also make for unhealthful working conditions. Whereas thebrushing line may be continuously maintained with only very briefperiods of down time, a pickling line must periodically be completelyshut down for relatively long periods to permit substantial replacementsand repairs. Thecost of the pickling acids, commonly sulphuric acid, hasin the past fluctuated considerably more than has been the case withsuitable brushing materials. Not only is the supply of sulphuric acidsometimes a problem, but also the large quantities of water necessaryare becoming steadily more difilcult to obtain, especially reasonablyclean water which will not leave objectionable residues. Whereas thewaste disposal problem of a pickling line is serious and becomingsteadily more so due to the imposition of anti-pollution laws, the scaleremoved by a brushing line is easily salvaged and becomes a valuablesource of powdered metal for use in powder metallurgy. It is also usefulas an abrasive and as a chemical. The installation cost of a-scaleremoval line of the general type disclosed herein may be as low asapproximately one-third that of a continuous pickling line having thesame production capacity.

Not only are there very important operating advantages arising from theemployment of my new apparatus and process, but also the finished workis much superior to that obtainable from a conventional pickling line.More particularly, the brushing action, properly controlled, serves tobeneficiate the metal surface by removal of minute splinters, theblending of sharp edges of pits,

other surface irregularities and strip margins, and the production of avery clean, dry finish which does not tend to rust quickly. Despite thewashing steps employed after acid pickling, it is not practical toremove all minute traces of acid, salts and water-borne dirt from themetal surface, and consequently the pickled surface is not clean and ishighly susceptible to rusting. The pickling process actually tends toproduce and accentuate objectionable pits in the surface in which saltscollect and a certain amount of hydrogen may be absorbed by the metalsurface with consequent local weaknesses and embrittlement.

The brushing stands fit in well with other high speed equipment such asslitters, for example, and the brushing operations may, of course, beselected not only to remove scale but also to afford an improved finishto the metal surface, to remove edge burs, and generally to eliminatethe need for further elaborate finishing operations at a later period.In contrast thereto,,the pickling line is often a bottleneck in a steelmill.

Referring now to Fig. 1 of the drawing, in a usual installationembodying the principles of my invention, the upper work rolls 28 and 29may be 6 inches in diameter or somewhat larger if a relatively widestrip is to be processed necessitating unusually long rolls. Lower workroll 22 will normally range from 1 /2 to 3 inches in diameter dependingupon the thickness of the steel strip to be processed. Thus, if thestrip is between .060 and .080 inch thick, roll 22 may be approximately1 /2 inches in diameter; if the strip is from .080 to .100 inch thick,such roll may be 1% inches in diameter; if the strip is .100 to .187inch thick, then such roll may be 2 /2 inches in diameter; and if suchstrip is .187 to .250 inch thick, then such roll may be 3 inches indiameter. I

As shown in Figs. 1 and 3 of the drawing, the strip may be caused toconform to an arcuate portion of the periphery of roll 22 of selecteddiameter as explained above. This does not require that rolls 28 and 29form true nips with roll 22 and they may preferably be spaced from thelatter distances somewhat greater than the thickness of the strip beingprocessed. The less the strip thickness, the smaller should be thediameter of work roll 22. There is, however, a method of avoiding thenecessity of employing very small diameter work rolls 22 or of avoidingthe necessity of changing from a larger to a smaller work roll 22 whenstrip of thinner gauge is to be processed. I have unexpectedlydiscovered that when the rate of travel of the strip through the machineis very considerably increased (as from 35 feet per minute to feet perminute in one case) the strip no longer conforms exactly to the uppersurface of small roll 22 but leaves such upper surface in an abrupt humpor buckle, thereby causing the concave surface to be flexed on a smallerradius than that of roll 22 itself. This has proven very effective infracturing and loosening scale, and I am enabled actually to detach from25 to 50 percent of the scale from such strip surface at this stage inthe process and prior to the subsequent brushing operations. Of course,the strip will also be flexed in a similar manner but in the oppositedirection in stand 80 (Fig. 6) so that the scale on both sides of thestrip will have been subjected to very substantial and forcefulcompression. Bar 56 will desirably extend downwardly as far as thecenter line of rolls 28, 29 to serve as a bumper or deflector limitingthe extent to which the strip is thus permitted to buckle or bulge. Thedegree of bulge may also be controlled by regulating the pressure of thesmall work roll against the strip, the greater the pressure the greaterbeing the tendency to bulge.

I have found that the work rolls 23 and 29 and backup roll 7 should bevery slightly crowned to ensure proper tracking of the strip and toprevent strip wobble. The upper work roll 28 (on the strip exit side ofthe machine) should rotate at a slightly greater speed (surface feet perminute) than roll 29 inasmuch as sufiicient scale will have been removedby the time the strip reaches roll 28 slightly to lessen the effectivegauge of such strip. This may desirably be achieved by driving rolls 23and 29 at the same rate of rotation from motor 40 through pinion stand45 but making roll 28 of very slightly greater diameter than roll 29 sothat its surface speed will be about 1 to 2 percent greater. Back-uproll 7 will be driven at a rate to drive small work roll 22 at the samespeed as roll 29. Roll 22, of course, has no positive drive means of itsown and is mounted so as to be quickly and conveniently removable. Whenroll 22 is changed to one of a different diameter as explained above, itis not necessary to change rolls 7 or 28 and 29.

In addition to removing a large portion of the scale, the abrupt reversebending of the strip regularizes the metal structure to a considerableextent and superficially work-hardens the strip a little although notenough to prevent the metal from still drawing well. Not only does suchabrupt reverse bending exert large edgewise compressive forces on thescale layers, but it also serves to cause minute slivers in the surfaceto stand up in a manner rendering them more amenable to the subsequentbrushing operation.

The roller leveler 83 considerably facilitates the subsequent brushingoperations and a leveler utilizing a large number of small diameterrollers is desirable.

The power driven rotary brushes 54 and 55 are of considerable importancein preventing the build-up of scale particles on the rolls. Suchbuild-up may otherwise be quite detrimental to the operation of my newmachine and may cause the fractured hard scale particles to be driveninto the surface of the bend being processed with permanent damage tothe latter. Brushes 59 and 60 combined with suction nozzles 57 and 58serve substantially to clean small work roll 22 (Fig. 3) and anyparticles transferred to the surface of large back-up roll 7 are, ofcourse, removed by power driven cylindrical rotary brush 54. The bronzeshoe 56 fitting between rolls 28 and 29 both prevents particlesdislodged by brush 55 from dropping down between rolls 28 and 29 uponstrip S, and also serves somewhat as a scraper. The greater quantity ofscale particles is, of course, dislodged from the underside of the stripin the Fig. 3 embodiment inasmuch as it is such underside which issubjected to compressive forces. The tensioning of the upper surface isalso somewhat effective but to a less degree.

The employment of my new process preliminary to the power brushing ofthe strip wherein I flex the strip about a radius of 1% inches or less(by traversing the strip at sufficiently high speed the strip may becaused to buckle about smaller radii than those indicated by the listeddiameters of work roll 22 given above) so uniformly and effectivelyfractures and loosens the scale from the metal surface that a subsequentbrushing opera- 8- tion properly carried out, as explained herein, iseffective to remove percent of the scale from the strip surface and alsoto produce a regularized and much improved metal surface. Themultitudinous objections to the usual pickling operation are entirelyavoided.

The small work roll will ordinarily be driven at substantially the samerate of surface feet per minute as the opposed larger work rolls, itbeing recalled that the larger work roll on the exit side will beturning at a slightly greater surface f.p.m. rate than the other workroll. The larger work rolls serve to deflect the strip about the smallerroll but preferably do not act to pinch or reduce the strip. They arearranged asymmetrically of the smaller work roll and back-up rollassembly. The exact diameter of the back-up roll is not critical butmay, for example, be 8 inches when the smaller work roll is 1 /2 to 3inches in diameter and the rolls are approximately 36 inches long. Therolls should, of course, be longer than the width of the stripprocessed. If non-fiat rod is to be processed, the rolls may beappropriately grooved to receive and guide the same.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I therefore particularly point out and distinctly claim as my invention:

1. Mechanism for sharply flexing metal strip and the like comprising astand, a back-up roll journalled in said stand, power means operative todrive said roll at a predetermined rate of speed, a parallel smallerdiameter work roll freely rotatably journalled in said stand and mountedfor ready removal therefrom, said work roll contacting said back-uproll, a pair of parallel larger work rolls slightly spaced from saidsmaller work roll asymmetrically of said smaller work roll and back-uproll assembly, power means separate from said firstnamed power meansoperative to rotate said two larger work rolls in unison together at apredetermined rate of rotation, and means operative to shift said largerwork rolls toward and away from said smaller work roll.

2. Mechanism for sharply flexing metal strip and the like comprising astand, a back-up roll journalled in said stand, power means operative todrive said roll at a predetermined rate of speed, a parallel smallerdiameter work roll freely rotatably journalled in said stand, said workroll contacting said back-up roll, a pair of parallel larger work rollsslightly spaced from said smaller work roll asymmetrically of saidsmaller work roll and backup roll assembly, power means separate fromsaid firstnamed power means operative to rotate said two larger workrolls at predetermined rates of rotation, and means operative to shiftsaid larger work rolls relative to said smaller work roll.

3. The mechanism of claim 2, wherein said smaller work roll has adiameter of from 1 /2 to 3 inches.

4. The mechanism of claim 2, wherein the said larger work roller at theexit side of the stand is driven at the same rate of rotation as theother said larger work roll but is of slightly greater diameter than theother said roll.

5. The mechanism of claim 2, including slides mounted in said standjournalling said larger work rolls for recip rocation toward and awayfrom said smaller work roll, and power means operative thus toreciprocate said slides.

6. The mechanism of claim 2, including slides mounted in said standjournalling said larger work rolls for reciprocation toward and awayfrom said smaller work roll, power means operative thus to reciprocatesaid slides, and means interconnecting said slides to ensure precisereciprocation in unison.

7. The mechanism of claim 2, including slides mounted in said standjournalling said larger work rolls for reciprocation toward and awayfrom said smaller work roll, slides in said stand journalling saidback-up roll for reciprocation in a direction toward and away from saidsmaller work roll, and power means operative thus to reciprocate saidslides.

8. The mechanism of claim 2, including power driven rotary brushesengaging said back-up roll and said two larger work rolls eifective toprevent accumulation of material on their surfaces.

9. In mechanism for sharply flexing metal strip and the like, a stand, aback-up roll journalled in said stand,

' power means operative to drive said roll, a parallel smaller diameterwork roll freely rotatably supported against said back-up roll, a pairof parallel larger work rolls slightly spaced from said smaller workroll sufficiently to avoid reduction of the work therebetweenasymmetrically of said smaller work roll and back-up roll assembly, andpower means operative to drive said larger work rolls.

10. The method of loosening scale on metal strip which comprisesdeforming such strip by flexing the same about a small diameter roll,and continuously advancing such strip at such a high rate of speed thatit bulges away from the surface of such small roll in reaction to theforce of deformation and is consequently abruptly flexed about a smallerradius than that of such roll.

11. Mechanism for flexing metal strip andthe like comprising a stand, aback-up roll journalled in said stand, power means operative to drivesaid roll at a predetermined rate of speed, a paralleled smallerdiameter work roll freely rotatably journalled in said stand, said workroll contacting said back-up roll, a pair of parallel larger work rollsslightly spaced from said smaller work roll asymmetrically of saidsmaller work roll and backup roll assembly, and means intergearing saidlarger work rolls for rotation at the same rate, said larger work rollon the exit side of the stand being of slightly greater diameter thanthe larger work roll on the entering side of the stand.

12. Mechanism for flexing metal strip and the like comprising a stand,spaced slides mounted for parallel reciprocation in said stand, aback-up roll journalled in said slides, power means operative to drivesaid roll at a predetermined rate of speed, a parallel smaller diameterwork roll freely rotatably supported against said back-up roll, a pairof parallel larger work rolls journalled in spaced slides in said standfor reciprocation toward and away from said smaller work rollasymmetrically of said smaller work roll and back-up roll assembly,drive means for said larger work rolls, means operative to reciprocatesaid slides in said stand, pinion-bearing torsion bars and racks on saidstand and slide reciprocating means respectively intergeared to ensurethat said slides at opposite ends of each said roll are reoiprocatedexactly in unison.

13. Mechanism for flexing metal strip and the like comprising a stand, aback-up roll journalled in said stand, power means operative to drivesaid roll at a predetermined rate of speed, a parallel smaller diameterwork roll freely rotatably journalled in said stand, said work rollcontacting said back-up roll, a pair of parallel larger work rollsslightly spaced from said smaller work roll asymmetrically of saidsmaller Work roll and back-up roll assembly, said back-up roll beingbeneath said smaller work roll and said larger work rolls beingthereabove,

drive means for said larger work rolls, a single cylindrical powerdriven rotary brush mounted to engage the upper surfaces of both saidlarger work rolls to clean their surfaces and prevent build-up ofmaterial thereon, and a shoe interposed between said larger work rollsand closely fitting the same to prevent particles dislodged by saidbrush from dropping down therebetween onto the upper surface of thework.

14. Mechanism for flexing metal strip and the like comprising a stand,spaced slides mounted for parallel reciprocation in said stand, aback-up roll journalled in said slides, power means operative to drivesaid roll at a predetermined rate of speed, a parallel smaller diameterwork roll freely rotatably supported against said back-up roll, journalsfor said smaller work roll releasably supported in said slides, a pairof parallel larger work rolls journalled in spaced slides in said standfor reciprocation toward and away from said smaller work rollasymmetrically of said smaller work roll and back-up roll assembly,drive means for said larger work rolls, and means operative toreciprocate said slides in said stand.

References Cited in the file of this patent UNITED STATES PATENTS1,047,335 Thurston Dec. 17, 1912 1,984,762 Roberts Dec. 18, 19342,004,596 Biggert June 11, 1935 2,226,500 Matthews Dec. 24, 19402,234,153 Herbert Mar. 4, 1941 2,256,520 Johansen Sept. 23, 19412,282,770 Sarver May 12, 1942 2,318,432 Stanier et a1. May 4, 19432,335,196 Pecsok Nov. 23, 1943 2,391,499 Yoder -a Dec. 25, 19452,403,374 Kalmar July 2, 1946 2,680,938 Peterson June 15, 1954 2,790,229Hellstrom Apr. 30, 1957 FOREIGN PATENTS 619,820 Germany Oct. 7, 19351,071,352 France Mar. 3, 1954

